Thrust and radial-bearing apparatuses are commonly used in a variety of mechanical applications. For example, subterranean drilling systems, turbomachinery, hydroelectric plants, wind mills, cranes, turbine generators, and power plant machinery may utilize bearing assemblies.
A conventional subterranean drilling system may include one or more thrust-bearing and/or radial-bearing apparatuses that are operably coupled to the downhole drilling motor for carrying loads generated during drilling operations. Radial-bearing apparatuses utilized in such drilling systems may each include a stator that does not rotate and a rotor that is surrounded by the stator and that is attached to the output shaft so as to rotate with the output shaft. The stator and rotor may each include a plurality of superhard bearing elements or inserts.
Wear-resistant, superhard materials are commonly utilized for bearing elements utilized in radial-bearing assemblies. A conventional polycrystalline diamond compact (“PDC”) radial-bearing assembly may include steel rotor and stator bearing rings that are each configured to accept a number of superhard bearing elements. Each superhard bearing element may include a polycrystalline diamond (“PCD”) layer formed on a cemented tungsten carbide substrate. One or more superhard bearing elements may be attached to a bearing rotor or stator by press-fitting, brazing, or through other suitable methods of attachment. Typically, bearing elements attached to a radial-bearing rotor have superhard bearing surfaces configured and oriented radially outward so as to bear against opposing superhard bearing surfaces of bearing elements attached to a radial-bearing stator that radially surrounds the radial-bearing rotor.
During drilling operations, an output shaft that transfers rotational torque from a drilling motor to a drill bit may be deflected at various angles relative to the rotational axis of a bearing apparatus. Over time, such repeated deflection of the output shaft may cause a radial-bearing rotor attached to the output shaft to become axially misaligned with respect to a radial-bearing stator surrounding the radial-bearing rotor. Axial misalignment of the radial-bearing rotor from the radial-bearing stator may result in a decrease in bearing performance or bearing failure.